Paleolimnology

1
Paleolimnology
2
PaleolimnologyLakes as Reservoirs of History

• Introduction
• Study of lake sediments
• Implications compares historic conditions with
  more modern changes
• Study of the impacts of
• Local pollution
• Worldwide pollution

3
Paleolimnology Techniques

• Pollen analysis of lake sediments
• Long useful to geologists and plant biologists
• Plant types indicate climatic conditions
• Diatom analysis
• Indicators of fertility and water temperature
• Ex Pennate to centric diatom ratios evidence
  of eutrophication

4
(No Transcript)
5
(No Transcript)
6

• Macro fossils fish, vertebrae and scales, wood
  fragments
• 14C dating
• Indicates age of sediments and organic fragments
• Also other isotopes
• Cladoceran mouth parts, abdominal claws
• Indication of community structure
• Ex size regression of Mysis stomach contents

7
Figure 7 Oligotrophic vs. Eutrophic Midge
Mouth Parts
8

• Known atomic events (bombs and accidents)
• Increase in radioactive isotopes
• Geologic events
• Dating of core sections
• Ex dating of Katmi and St. Helens eruptions
• 210Pb dating
• From earliest human use to tetra-ethyl-lead
  gasoline additives

9
(No Transcript)
10
(No Transcript)
11

• Chlorophyll and carotenoid degradation products
• Pigments are community indicators
• Chlorophyll has been found in samples as old as
  11,000 years! (J.R. Valentyne)
• Varves
• Alternating light and dark layers corresponding
  to a year
• Dark reducing conditions
• Light spring inflows
• Indicators of annual deposition

12
(No Transcript)
13
(No Transcript)
14

• Inorganic chemistry
• Ex Greenland ice studies
• Previous lake levels, wave-cut terrace
• Ex Lake Tahoe has a 100m high terrace and also
  dramatically lower lake levels
• Organic content
• Peat layers

15
(No Transcript)
16
(No Transcript)
17
Ancient Lakes and Speciation

• Baikal
• 25 million years old
• 2,500 endemic species
• Geography
• Geology
• Physical Chemistry
• Rift Valley lakes
• Tanganyika and Nassa
• Central Andes
• Titicaca

18
(No Transcript)
19
(No Transcript)